Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
import copy
h,w = (int(i) for i in input().split())
x = [input() for i in range(h)]
cf,list1,num = [[0,0]],[[0,0]],1
while [h-1,w-1] not in cf and len(list1) != 0:
	list2 = []
	for j in list1:
		list3 = [[j[0]+1,j[1]],[j[0]-1,j[1]],[j[0],j[1]+1],[j[0],j[1]-1]]
		for j2 in list3:
			if (-1<j2[0]<h) and (-1<j2[1]<w) and (j2 not in cf) and (x[j2[0]][j2[1]]=="."):
				cf.append(j2)
				list2.append(j2)
	num += 1
	list1 = copy.deepcopy(list2)
num2 = 0
for k in x: num2 += k.count(".")
if [h-1,w-1] not in cf: answer = -1
else: answer = num2-num
print(answer)